The superstar boxer and his smokin' hot baby mama, Erica Mendez, are having the time of their lives out on vacation in Puerto Rico ... dancin' it up and putting it on display for all to enjoy.

And, yeah ... we're enjoying it, alright.

FYI -- Swift and the singer/model have been dating for years and have one child together.

But, it was Mom and Dad having all the fun on Wednesday ... showing off some serious moves to "Ella Quiere Beber" by Anuel AA and sippin' on some drinks.

Garcia (35-2) served up a knockout win in his last fight against Adrian Granados, but it's Mendez servin' up the KO looks this time around.

So, sit back and enjoy, wherever you are, and live vicariously through these guys. They're doing it right.